Deputy Permanent Representative of the Democratic People's Republic of Korea Ri Tong Il responds to a question during a March 24 news conference at United Nations headquarters. (Richard Drew / AP)

UNITED NATIONS — North Korea accused the United States Monday of undermining the prospect of improved relations with South Korea and the revival of six-party talks on its nuclear program by escalating “hostile” military activity and policies.

Pyongyang’s deputy U.N. ambassador Ri Tong Il said at a news conference that the North’s nuclear weapons are not a “political bargaining chip.”

He warned that as long as the U.S. continues “nuclear blackmails,” North Korea will continue to take “additional measures” — which he refused to disclose — “in order to demonstrate the power of the self-defensive nuclear deterrent.”

Ri contrasted the welcome the international community gave to February’s high-level talks between North Korea and South Korea that led to a revival of family reunions and “great expectations of the entire Korean nation toward wide-open dialogue, easing of tensions ... reconciliation and unification of the country” with the U.S. refusal to halt military drills with South Korea as Pyongyang requested.

As North Korean and South Korean representatives were meeting, Ri said, the U.S. flew nuclear-weapon carrying B-52 bombers over South Korea “undermining the climate of change towards relaxation.” And while separated families were meeting at Diamond Mountain, the U.S. went ahead with drills that included nuclear-armed submarines and the newest missile-carrying destroyers, he said.

Using the initials of the Democratic People’s Republic of Korea, the country’s official name, Ri said the United States is intent “on politically eliminating the DPRK as a regime, economically stifling the DPRK, and militarily annihilating the DPRK.”

Without naming President Barack Obama but referring directly to him, Ri said, “As long as the U.S. government is in pursuit of so-called strategic patience, dreaming of the change of DPRK, the DPRK will take and exercise high degree of patience, waiting until a man of normal and reasonable vision and idea enters into the seat of ... the White House.”

The U.S. Mission to the United Nations had no immediate comment.

North Korea walked away from the six-party nuclear disarmament talks in 2009 over disagreements on how to verify steps the North was meant to take to end its nuclear programs. The U.S. and its allies are demanding that the North demonstrate its sincerity in ending its drive to acquire nuclear weapons.

Ri said U.S. preconditions are a pretext “to justify their rejection of the dialogue.”

“DPRK has been treating and remaining open to six-party talks without setting any preconditions,” he said. “And still DPRK is open, but I don’t believe ... U.S. will come to the table.”

Since pulling out of the six-party talks, the North has conducted a long-range rocket test, its second-ever nuclear test, and most recently launches of short-range rockets which Ri called a “routine exercise.”

Last month, a U.N. commission of inquiry warned North Korean leader Kim Jong Un that he may be held accountable for orchestrating widespread crimes against civilians in the secretive Asian nation, ranging from systematic executions to torture, rape and mass starvation.

Ri said the DPRK’s National Defense Commission issued a statement on March 14 calling for the U.S. “to roll back all its anachronistic and outdated hostile policies” including its “human rights conspiracy” against North Korea.

He claimed the U.S. paid nongovernmental organizations to go to North Korea’s border with China, abduct and brainwash citizens from the North and then send them to South Korea for further brainwashing so they can be used in interviews. As for North Korean defectors, he dismissed them as criminals fleeing justice.